_________________________________________________________________________________________________

*Corresponding author e-mail: rania_almoselhy@outlook.com

Receive Date: 19 February 2021, Revise Date: 01 March 2021, Accept Date: 03 March 2021

DOI: 10.21608/EJCHEM.2021.64084.3373

©2021 National Information and Documentation Center (NIDOC)

Egypt. J. Chem. Vol. 64, No. 3 pp. 1639 - 1652 (2021)

Determination of 3-MCPD in Some Edible Oils using GC-MS/MS

Rania I.M. Almoselhya,*, Mounir M. Eida, Walid S. Abd El-Baseta and AlaaEldean F.A.

Aboelhassanb

a Oils and Fats Research Department, Food Technology Research Institute,

Agricultural Research Center, Giza, Egypt b Central Laboratory of Residue Analysis of Pesticides and Heavy Metals in Food,

Agricultural Research Center, Giza, Egypt

HE presence of 3-monochloropropanediol (3-MCPD) in edible oils has been widely

12345reported with its potential health risks. The aim of this study was to apply optimized recent

updated and validated enhanced swift analytical indirect method for determining 3-MCPD in

consumed edible oils (palm, palm olein, extra virgin olive, corn, sunflower, soybean, olive

pomace) and blend of 5% sunflower oil with extra virgin olive oil, using selective and sensitive

gas chromatography tandem triple quadrupole mass spectrometry (GC-MS/MS) employing

deuterated 3-MCPD (3-MCPD-d5) as internal standard (IS) during the entire analytical procedure

to obtain precise and accurate results. The occurrence and variation of 3-MCPD contents among

the studied oils were found in different levels ranged from 93.1 µg/kg to 5634.1 µg/kg oil

samples, with maximum value assigned for palm oil (5634.1 µg/kg) followed by palm olein

(5576.8 µg/kg), corn oil (2447 µg/kg), sunflower oil (1817.3 µg/kg), soybean oil (1486.1 µg/kg),

olive pomace oil (572.5 µg/kg), blend of 5% sunflower oil with extra virgin olive oil (210 µg/kg)

and extra virgin olive oil (93.1 µg/kg). Palm, palm olein, corn, sunflower and soybean oils were

found out of the limits recommended by the Commission Regulation (EU) 2020/1322, whereas,

extra virgin olive oil, olive pomace oil and blend of 5% sunflower oil with extra virgin olive oil

were in compliance and within the limits recommended by EU. Moreover, 3-MCPD content could

be used as a good tool for authenticity and quality of genuine extra virgin olive oil.

Keywords: Edible oils; 3-Monochloropropanediol (3-MCPD); GC-MS/MS; Food contaminants

Introduction

3-Monochloropropanediol (3-MCPD) is the

most toxic food contaminant formed during thermal

processing of refined edible oils. Refining of edible

oils at a high temperature generates byproducts such

as 3-MCPD [1, 2]. 3-MCPD with molecular formula

of C3H7ClO2, molar mass of 110.539 g mol-1, density

of 1.32 g cm-3, and boiling point of 213 oC exists

either in free form, or in bound form called 3-MCPD

esters in different foodstuffs that has passed through

cooking processes using cooking oil. In order to

produce safe edible oils, usage of new materials and

methods in refining process are explored, and the

effects of byproducts generated during this process

on human body are closely monitored [3].

Deodorization is a key step during oil refining for

overall oil quality, especially the deodorization

temperature is the direct and critical parameter [4].

The UK Committee on Carcinogenicity of Chemicals

in Food, Consumer Products and the Environment [5]

have considered the carcinogenicity of 3-MCPD and

its fatty acid esters. European Commission [6], the

regulatory arm of the European Union, namely the

European Commission (EC) Scientific Committee on

Food (SCF), adopted the tolerable daily intake (TDI)

of 2 µg/kg body weight (bw) for 3-MCPD.

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Furthermore, The Joint WHO/FAO Expert

Committee on Food Additives (JECFA) also

recommended a provisional maximum TDI of

2 µg/kg bw for 3-MCPD [7, 8]. In March 2016, the

European Food Safety Authority (EFSA) issued an

extensive report warning about the possible health

consequences of contaminants created during the

processing of edible oils [9, 10]. EFSA specifically

identified 3-MCPD, which was classified as a

possible human carcinogen by International Agency

for Research on Cancer (IARC) and documented in

IARC Monographs [11]. Finally, there is a growing

concern associated with the release of bound

3-MCPD into its free form that results in

bioavailability and absorption of 3-MCPD into

human body fluids and tissues, e.g. human breast

milk, which requires additional studies [12-14].

Kidney is one of the primary target organs

for 3-MCPD [15] with induced renal injury [16],

toxicity in kidney, lung, testis, and heart [17-19],

immunosuppressive activity [20], toxic effects on

male reproduction [21] and is regarded as a rat

carcinogen inducing testicular lesions, Leydig-cell

and mammary gland tumors in males and kidney

tumors in both genders [22, 23]. Combination of

histopathological examination, clinical chemistry and

metabolomics analyses resulted in systematic

comprehensive assessment of the long-term toxicity

of 3-MCPD, where renal tubular hyaline cast

accumulation with epithelium cell degeneration and

potential kidney toxicity were major

histopathological changes with thin appearance and

subdued behavior accompanied by decreases in bw.

Microscopy revealed tubular basophilia in kidneys,

exfoliated degenerative germ cells in the lumen of the

seminiferous tubule of testes, vacuolation in the

brain, axonal degeneration of sciatic nerve and

cardiomyopathy [24, 25].

Current analytical methods for 3-MCPD

determination still need to be improved regarding

sample preparation. The methods based on liquid

extraction should be replaced with more efficient and

environment-friendly. Currently, the widely applied

method developed by DGF is time-consuming and

requires the use of significant amounts of solvents.

Undoubtedly, the methods should be as cheap and

simple as possible in order to apply them in industrial

laboratories for routine analyses of complex matrices

of foodstuffs. Moreover, the formation routes and

mechanisms need to be fully explained in relation to

industrial processing, with the aim of mitigating the

presence of 3-MCPD in foodstuffs by changing the

process conditions, as in oil refining process [26-29]

or by treating the already processed product, as oils

after refining process on adsorbent material or with

enzymes [30, 31].

Accurate, rapid, and high-sensitivity

chemical analytical methods are needed for detecting

the presence and levels of 3-MCPD esters in different

types of food. To date, the reported analytical

methods for 3-MCPD esters can be divided into

indirect and direct detection approaches. The indirect

method involves releasing the free 3-MCPD from all

the fatty acid esters of 3-MCPD in the sample,

preparing derivatives for analysis, and quantifying

the amount of free 3-MCPD, with the total amount of

3-MCPD esters to be reported as the equimolar of

free 3-MCPD contents. On the other hand, the direct

approach characterizes and quantifies each individual

3-MCPD ester in food samples directly, which is

straightforward and easy to understand but much

more difficult in sample purification and method

development during practical utilizations compared

to that for the indirect approach [32].

Commission Regulation (EU) 2020/1322 of

23 September 2020 amending Regulation (EC) No.

1881/2006 as regards maximum levels of

3‐ monochloropropanediol (3-MCPD), 3-MCPD

fatty acid esters and glycidyl fatty acid esters in

certain foods, recommended the following in

“Section 4: 3-monochloropropanediol (3-MCPD),

3-MCPD fatty acid esters and glycidyl fatty acid

esters” [33].

4.3.1. Vegetable oils and fats, fish oils and oils

from other marine organisms placed on the market

for the final consumer or for use as an ingredient

in food falling within the following categories,

with the exception of the foods referred to in 4.3.2

and of virgin olive oils, the maximum level is

1250 μg/kg of 3-MCPD.

- oils and fats from coconut, maize, rapeseed,

sunflower, soybean, palm kernel and olive oils

(composed of refined olive oil and virgin olive

oil) and mixtures of oils and fats with oils and

fats only from this category; the maximum level

is 1250 μg/kg of 3-MCPD.

- other vegetable oils (including pomace olive

oils), fish oils and oils from other marine

organisms and mixtures of oils and fats with oils

and fats only from this category; the maximum

level is 2500 μg/kg of 3-MCPD.

4.3.2. Vegetable oils and fats, fish oils and oils

from other marine organisms destined for the

production of baby food and processed

cereal-based food for infants and young children,

the maximum level is 750 μg/kg of 3-MCPD.

The aim of this study was to investigate the

occurrence of 3-MCPD in some edible oils using

recent optimized validated indirect method of

determination and comparison of 3-MCPD contents

among different edible oils and their compliance with

Determination of 3-MCPD in Some Edible Oils using GC-MS/MS

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standard regulations recommended by Commission

Regulation (EU) 2020/1322 [33].

Materials and Methods

Materials

Edible oils from various plant origins were

purchased from local markets and used in the study.

Palm oil, palm olein oil, extra virgin olive oil

(EVOO), corn oil, sunflower oil, soybean oil, olive

pomace oil and blend of EVOO + 5% sunflower oil.

Chemicals and reagents

All solvents and chemicals were of

Analytical and HPLC grades obtained from Sigma

Chemical Co. (USA). Sodium methoxide, glacial

acetic acid, acetone, diethyl ether, ethyl acetate,

t-butyl methyl ether, n-hexane, phenylboronic acid

(PBA), 3-MCPD and 3-MCPD-d5 were purchased

from Sigma Chemical Co. (USA), while

3-MCPD-1,2-dipalmitoyl ester and 3-MCPD-1,2-

dipalmitoyl ester-d5 were purchased from Toronto

Research Chemicals Inc. (Canada).

Physicochemical quality parameters and fatty acid

composition

Refractive index (RI), and peroxide value (PV)

expressed as milliequivalent of O2/kg oil, were

determined according to AOAC [34]. Acidity or free

fatty acid (FFA) expressed as oleic acid %, was

determined according to ISO 660:2020 [35].

Conjugated constituents were determined by

measuring UV absorption at 232 nm for diene and

270 nm for triene in purified solvent according to

ISO 3656:2011 [36]. Fatty acid composition was

converted into methyl ester and determined by GC

according to ISO 12966-2:2017 [37].

Determination of 3-MCPD

3-MCPD contents in edible oils samples

under study were determined according to the

analytical procedures described by Aboelhassan et al.

[38], where an enhanced swift analytical method for

the determination of bound 3-MCPD has been

optimized. The method enhancements include shorter

sample preparation time, a rapid run program in triple

quadrupole GC-MS/MS, besides, augmented

selectivity and sensitivity. It has been verified for

fitness-for-use in terms of selectivity, sensitivity,

accuracy, range and measurement uncertainty for

compliance with the international performance

requirements, the limit of quantification (LOQ) and

the limit of detection (LOD) were estimated to be less

than 2 and 0.5 μg/kg, respectively. The recoveries at

different spiked levels ranged from 98 to 106%. The

reproducibility (expressed as relative standard

deviation RSD) was less than 8% while measurement

uncertainty was in the range of ±18% [38].

Standard solutions preparation

100 μg/mL stock solutions of 3-MCPD and

3-MCPD-d5 were prepared by their individual

dissolving in deionized water and stored in the

refrigerator. 1 μg/mL solutions of 3-MCPD and

3-MCPD-d5 were prepared by diluting appropriate

volumes in deionized water and stored in the

refrigerator. Calibration standard solutions with

concentrations of 1, 5, 10, 20 and 50 μg/L were

prepared by diluting 1 μg/mL 3-MCPD standard

working solution with deionized water. 100 and 132

μg/mL standard solutions of 3-MCPD-1,2-

dipalmitoyl ester and 3-MCPD-1,2-dipalmitoyl ester-

d5, respectively, were prepared by dissolving both of

them separately in 25 mL of tert-butyl methyl ether

and stored in the refrigerator. 1 and 1.3 μg/mL

standard solutions of 3-MCPD-1,2-dipalmitoyl ester

and 3-MCPD-1,2-dipalmitoyl ester-d5, respectively,

were prepared by diluting appropriate volumes in

tert-butyl methyl ether and stored in the refrigerator.

Calibration standards derivatization for standard

curves

An exact volume of 2 mL was taken

separately from each 3-MCPD calibration standard

solution into 4 mL capped vials. A 40 μL aliquot of

3-MCPD-d5 (1 μg/mL) was added as an internal

standard, followed by the addition of 400 μL of 20%

PBA. The mixture was well shaken for 1 min,

transferred into a water bath, kept at 85°C for 20 min

and left to cool at room temperature. A 2 mL aliquot

of n-hexane was added, and the mixture was well

shaken for 1 min. n-Hexane layer was filtered

through a 0.45 μm membrane filter before injection

into triple quadrupole GC-MS/MS.

Sample preparation

For 3-MCPD extraction, 2 ± 0.1 g of sample

(oil) was weighed in a 50 mL centrifuge tube, 777 μL

of 1.3 μg/mL 3-MCPD-1,2-dipalmitoyl ester-d5 was

added as an internal standard, then, 8 mL of diethyl

ether was added. The mixture was well shaken for

2 min. followed by addition of 200 μL of 2M sodium

methoxide. After 1-2 min., 100 μL of glacial acetic

acid was added, then the mixture was added to 10 mL

of deionized water added prior to a tube, with well

shaking for 2 min., followed by centrifugation at

4000 rpm for 5 min., then 2 mL of aqueous layer was

taken into a 4 mL capped vial and 400 μL of 20%

PBA was added. The vial was put into a water bath at

85°C for 20 min. It was left to cool, then 2 mL of

n-hexane was added, followed by well shaking for

1 min., and then n-hexane layer was filtered through

a 0.45 μm pore size membrane before injection.

Instrumentation

Chromatographic separation and mass

spectrometric determination techniques were applied

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using a gas chromatography tandem triple quadrupole

mass spectrometry system (7890B Triple Quadrupole

GC-MS/MS - Agilent Technologies, USA).

Inlet system was split/splitless with inlet

deactivated (inert) liner (Agilent Technologies, USA)

with an Agilent Column J&W Ultra Inert DB-35MS

GC column (20.0 m length, 0.18 mm internal

diameter and 0.18 μm film thicknesses).

For multiple reaction monitoring transitions;

2 MRM transitions were used (2 precursor ions and 2

product ions), one for quantification (a) and the other

for qualification (b). MRM details are represented in

Table 1.

Table 1. Multiple reaction monitoring transitions

Analyte Precursor ion, m/z Product ion, m/z Dwell time, ms Collision energy, eV

3-MCPDa 196 147 80 20

3-MCPDb 198 147 80 20

3-MCPD-d5a 203 150 80 20

3-MCPD-d5b 201 150 80 20

afor quantification, bfor qualification

Results and Discussion

Physicochemical quality parameters

Physicochemical quality parameters of the

studied oils were listed in Table 2.

Refractive index plays an important role in

characterizing oils, it has relationship to structure.

The obtained refractive indices of the studied oils;

PO, POO, EVOO, CO, SO, SPO, OPO and

EVOO+5%SO were 1.4550, 1.4580, 1.4678, 1.4720,

1.4727, 1.4725, 1.4726 and 1.4685, respectively.

These variations in refractive indices of the

corresponding oils under investigation were

attributed to their structure, chain length and the

differences in fatty acid composition of these oils

containing different profiles, especially linoleic acid

(C18:2) content. Peroxide value gives the initial

evidence of rancidity in unsaturated fats and oils. It

gives a measure of the extent to which an oil sample

has undergone primary oxidation. All investigated

oils in the study showed a low peroxide values as

illustrated in Table 2. The low peroxide values

indicated the high initial quality and freshness of the

studied oils. Also, the amounts of free fatty acids

were found generally too small. The observed low

acidity indicated that the oils did not undergo

hydrolytic processes and may have a long shelf life

emphasis the high quality of oils. It was ranged from

0.04 to 0.59% in the studied oils. Acidity is a

measure of the amount of free fatty acids (FFA)

present in oil due to both hydrolysis of its

triglycerides and oxidation of double bonds of the

unsaturated acyl chains which produced free fatty

acids with low molecular weight. It has been

frequently used as an important parameter to monitor

quality of oils and to show the case of hydrolysis and

oxidation induced in the oil. FFA content increases

with hydrolysis of triacylglycerols (TAGs) and

diacylglycerols (DAGs) [39]. FFA (or possibly free

hydrogen chloride) is necessary for formation of

3-MCPD ester which is formed 2–5 times faster from

DAGs than from monoacylglycerols (MAGs) or

TAGs [40, 41]. Absorbencies at 232 nm of PO, POO,

EVOO, CO, SO, SPO, OPO and EVOO+5%SO were

1.142, 1.022, 1.399, 1.690, 1.891, 1.661, 1.88 and

1.487, respectively. Whereas, absorbencies at 270 nm

of PO, POO, EVOO, CO, SO, SPO, OPO and

EVOO+5%SO were 0.165, 0.132, 0.134, 0.304,

0.284, 0.237, 0.281 and 0.180, respectively. Specific

extinction is a quality parameter that provides

information about oxidative state of oils and can aid

in detection of fraud [42]. The initial characteristics

of vegetable oils used in this study indicated that all

the oils were of good quality [43-49].

Table 2. Physicochemical quality parameters of the studied oils

EVOO+5% SO OPO SBO SO CO EVOO POO PO Parameter

1.4685

25 oC

1.4726

25 oC

1.4725

25 oC

1.4727

25 oC

1.4720

25 oC

1.4678

25 oC

1.4580

40 oC

1.4550

40 oC RI

0.26 0.05 0.04 0.06 0.08 0.29 0.59 0.37 FFA (oleic acid %)

1.05 1.08 0.77 1.05 0.87 3.86 1.01 1.80 PV [meq O2/kg oil]

1.487 1.88 1.661 1.891 1.690 1.399 1.022 1.142 UV Abs232 (Diene)

0.180 0.281 0.237 0.284 0.304 0.134 0.132 0.165 UV Abs270 (Triene)

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PO: Palm oil, POO: Palm olein oil, EVOO: Extra virgin olive oil, CO: Corn oil, SO: Sunflower oil,

SBO: Soybean oil, OPO: Olive pomace oil

Fatty acid composition

. Table 3. Fatty acid composition (%) of the studied oils

EVOO+5% SO OPO SBO SO CO EVOO POO PO Fatty Acid

*ND *ND *ND *ND *ND *ND 0.15 0.029 C 8:0

*ND *ND *ND *ND *ND *ND 0.17 0.023 C 10:0

*ND *ND *ND *ND *ND *ND 0.19 0.241 C 12:0

0.06 0.01 0.07 0.13 0.08 0.06 0.98 1.09 C 14:0

13.36 15.2 9.88 6.86 10.97 15.36 39.06 42.08 C 16:0

1.10 1.21 0.09 0.10 0.09 1.22 0.22 0.166 C 16:1

0.05 0.06 0.09 0.03 0.06 0.06 0.09 0.10 C 17:0

0.07 0.1 0.05 0.02 0.04 0.09 ND ND C 17:1

2.50 2.41 4.08 3.40 1.96 2.34 4.16 4.33 C 18:0

67.96 70.08 24.31 27.14 28.66 70.03 43.44 41.25 C 18:1

12.46 8.94 54.49 60.77 55.67 8.88 10.60 9.95 C 18:2

0.47 1.0 5.25 0.19 0.76 0.90 0.24 0.189 C 18:3

0.31 0.48 0.35 0.29 0.38 0.47 0.37 0.34 C 20:0

0.28 0.36 0.18 0.16 0.24 0.36 0.16 0.126 C 20:1

0.39 0.14 0.43 0.67 0.20 0.12 0.06 *ND C 22:0

17.77 18.3 14.90 11.38 13.65 18.41 45.39 48.359 Σ SFA

81.24 81.69 85.08 88.59 85.46 81.49 54.44 51.515 Σ USFA

*ND: Not Detected, PO: Palm oil, POO: Palm olein oil, EVOO: Extra virgin olive oil, CO: Corn oil,

SO: Sunflower oil, SBO: Soybean oil, OPO: Olive pomace oil, SFA: Saturated fatty acids,

USFA: Unsaturated fatty acids

Fatty acid compositions (%) of the studied

oils were shown in Table 3. All the studied oils had

elevated amounts of total unsaturated fatty acids

(Σ USFA) ranged from 88.59% in SO to 51.515% in

PO. Whereas, total saturated fatty acids (Σ SFA)

ranged from 48.359% in PO to 11.38% in SO.

From the composition point of view for unsaturated

fatty acids; oleic acid (C18:1) was the major in EVOO

˃ OPO ˃ EVOO+5%SO ˃ POO ˃ PO ˃ CO ˃ SO ˃

SBO, whereas, linoleic acid (C18:2) was the major in

SO ˃ CO ˃ SBO ˃ POO ˃ PO ˃ EVOO+5%SO ˃

OPO ˃ EVOO and linolenic acid (C18:3) was the

major in SBO ˃ OPO ˃ EVOO ˃ CO ˃

EVOO+5%SO ˃ POO ˃ SO ˃ PO. From the

composition point of view for saturated fatty acids;

palmitic acid (C16:0) was the major in PO ˃ POO ˃

EVOO ˃ OPO ˃ EVOO+5%SO ˃ CO ˃ SBO ˃ SO,

whereas, stearic acid (C18:0) was the major in PO ˃

POO ˃ SBO ˃ SO ˃ EVOO+5%SO ˃ OPO ˃ EVOO

˃ CO and myristic acid (C14:0) was the major in PO ˃

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POO with traces in the remaining oils. The obtained

results for fatty acid composition of the studied oils

were in their standard range [43, 45, 46, 49, 50].

Determination of 3-MCPD

The calibration curve of 3-MCPD was

shown in Figure (1). The results of calibration curve

revealed that there was a linear relationship between

different concentrations of 3-MCPD with R2 being

0.99989356.

3-MCPD contents (μg/kg) in the studied oils

were shown in Table 4 and Figures (2-9).

Table 4. Contents of 3-MCPD (μg/kg) in the studied oils

Edible oil 3-MCPD

(μg/kg)

3-MCPD Maximum level (μg/kg) recommended by

Commission Regulation (EU) 2020/1322

PO 5634.1 1250

POO 5576.8 1250

EVOO 93.1 1250

CO 2447.0 1250

SO 1817.3 1250

SBO 1486.1 1250

OPO 572.5 2500

EVOO+ 5% SO 210.0 1250

PO: Palm oil, POO: Palm olein oil, EVOO: Extra virgin olive oil, CO: Corn oil, SO: Sunflower oil,

SBO: Soybean oil, OPO: Olive pomace oil

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Results revealed the occurrence and

variation in 3-MCPD content among the studied oil

samples with different levels ranged from 93.1 µg/kg

to 5634.1 µg/kg , with maximum value assigned for

PO (5634.1 µg/kg) followed by POO (5576.8 µg/kg),

CO (2447 µg/kg), SO (1817.3 µg/kg), SBO (1486.1

µg/kg), OPO (572.5 µg/kg), EVOO+5% SO (210

µg/kg) and EVOO (93.1 µg/kg). Palm, palm olein,

corn, sunflower and soybean oils were found out of

the limits recommended by Commission Regulation

(EU) 2020/1322, whereas, extra virgin olive, olive

pomace and blend of 5% sunflower with extra virgin

olive oils were found within the recommended limit

by Commission Regulation (EU) 2020/1322 [33].

3-MCPD contents detected in oils were

ordered from the highest to lowest as follows: PO ˃

POO ˃ CO ˃ SO ˃ SBO ˃ OPO ˃ EVOO+5%SO ˃

EVOO. The available data have strongly suggested

that processing affects the overall 3-MCPD ester

levels in oils and foods. Refined commercial olive,

sunflower and soybean oils have relatively greater

(3–32 times) concentrations of 3-MCPD esters than

their unrefined counterparts [32].

The obtained results agreed with those

reported by WHO: Concentrations of 3-MCPD esters

in refined oils increase incrementally as follows:

soybean oil < sunflower oil < palm oil [8].

OPO which comes from poorer starting raw

materials had much higher content of 3-MCPD than

EVOO. It is probably due to the use of high

temperatures during both the drying process, which

has to be carried out before the solvent extraction

step, and during the deodorization step in refining

process. This is useful in considering

3-MCPD content as an analytical tool and

complementary indicator of adulteration in EVOO

where refined oils have been added [42, 51], and it

may be used as a good tool for authenticity, identity

and quality parameters of EVOO with many methods

such as UV-visible, FTIR spectroscopy, 1HNMR,

DSC [52-56].

PO and POO have highest 3-MPCD contents

which are more than double of CO and more than

triple of SO and SBO, agreed with Hew et al. [57].

The mechanism for the formation of

3-MCPD esters and palm oil related compounds is

assumed that glycerol, MAGs, DAGs and

phospholipids are precursors on the way to the esters.

The formation of free 3-MCPD strongly depends on

temperature and the content of lipids, glycerol, salt

and water. Additionally to triacylglycerols (TAGs),

fats and oils contain varying amounts of free fatty

acids, MAGs and DAGs depending on the history of

the raw material before processing. While oils like

rapeseed, sunflower, olive or soybean oil contain

between 1 and 3% DAGs, in palm oil amounts

between 6 and 10% can be found resulting from the

activity of lipases after maturation before

inactivation. Crude coconut, palm and palm kernel

oils are distinguished by high amounts of free fatty

acids up to 7%, while the other oils only contain

between 1 and 2% [58].

Following the study of factors impacting the

formation of 3-MCPD during palm oil production, a

root-cause analysis was performed in order to map

the parameters potentially responsible for the

occurrence of MCPD diesters in refined palm oil and

related fractions [59] shown in Figure (10).

Chlorine-containing compounds exist in the

form of either inorganic or organic. Inorganic

chlorine salts of calcium chloride (CaCl2),

magnesium chloride (MgCl2), iron (III) chloride

(FeCl2) and iron (III) chloride (FeCl3) originate from

fertilizers and irrigation process. FeCl2 and FeCl3

were reported to have higher contents compared to

other sources of inorganic chlorine. The occurrence

of organochlorines in crude palm oil (CPO) prior to

processing indicates that the chlorinated compounds

might be present in the oil palm fruitlets even before

harvesting. The correlations between total chlorine

content in vegetable oil and 3-MCPD level have also

been established by many researchers. It was

suggested that organochlorines might indirectly act as

a chlorine donor during oil deodorization process,

which takes place at a temperature above 180 oC.

During the process, the sum of organochlorines

depleted as the sum of 3-MCPD diesters increased

and HCl was formed. Therefore, HCl is suspected to

be one of the reactive compounds contributing to the

formation of 3-MCPD. It has also been identified that

the 3-MCPD ester level increases with the addition of

ionic bound chlorine, for instance

tetrabutylammonium chloride (TBAC) during the

modeling of deodorization for vegetable oil.

A similar finding, involving a laboratory scale of

CPO physical refining highlighted the potential of

natural organochlorine as a chlorine precursor due to

its oil solubility, which inhibits its removal during

rinsing step with water. Conventionally, among

fertilizers used in the oil palm plantation are

ammonium chloride, NH4Cl and potassium chloride,

KCl. In addition, the herbicides used in the

plantation, namely diuron,2,4-D amine, dicamba and

fluroxypyr also contained chlorine compound. As

most of the herbicides used in the plantation are

water soluble, the oil palm fruitlet is likely to be

exposed to the chlorine compound through nutrient

uptake by the palm trees and through leaching

process, where the chlorine compound dissolved in

groundwater which will then be absorbed by the palm

trees during cultivation. The irrigation water used in

the oil palm plantations is also a possible source of

chlorine precursor, in addition to the treated

wastewater from the treatment facilities that used

FeCl3 as flocculants. Moreover, the bruising of fresh

fruit bunches (FFBs) was identified to correspond

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Egypt. J. Chem. 64, No. 3 (2021)

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with the increase in FFA content in the palm oil

during harvesting and transportation to the mills. The

FFA formation is equivalent to the formation of

diacylglycerols (DAGs) and monocylglycerols

(MAGs), which influence the formation of 3-MCPD

[60, 61].

Determination of 3-MCPD in Some Edible Oils using GC-MS/MS __________________________________________________________________________________________________________________

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Egypt. J. Chem. 64, No. 3 (2021)

1647

Rania I.M. Almoselhy et al. _____________________________________________________________________________________________________________

________________________________________________

Egypt. J. Chem. 64, No. 3 (2021)

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Conclusions and Recommendations

Considering the aim of this study to

investigate the occurrence and contents of 3-MCPD

in some edible oils, and their compliance with

standard regulations recommended by Commission

Regulation (EU) 2020/1322, higher concentrations

of 3-MCPD have been reported for refined edible

oils (PO, POO, CO, SO, SBO), compared to

unprocessed oil (EVOO) which supports the

hypothesis that processing conditions play important

roles in the occurrence and formation of 3-MCPD.

A recent optimized validated indirect method of

determination of 3-MCPD using GC-MS/MS has

been verified for fitness-for-use in terms of short

sample preparation time, selectivity, sensitivity and

accuracy. It is recommended that appropriate efforts

to reduce concentrations of 3-MCPD in edible oils

continue to be implemented with additional

international collaborative studies on refining of

edible oils and analysis for 3-MCPD in relevant

oil-containing foods to form database for use in

future evaluations.

Conflict of Interest

The authors declare no conflict of interest.

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